Double Acting Air Powered Hydrotest Pump

A double-acting air powered hydrotest pump setup can be used anywhere hydraulic pressure needs to move a cylinder in both directions. In a cabinetized system, the pump, regulator, selector valve, reservoir, gauges, and pressure-control components are kept together so the operator can control the hydraulic circuit from one location.

The exact layout can vary by system, but the setup shown here uses an air-driven hydraulic pump with controls for advancing and retracting double-acting cylinders.

Key Components

• Reservoir — Holds the hydraulic oil used by the system and supplies fluid as the cylinders advance and retract.
• Selector valve — Directs oil to either side of the double-acting cylinder. A closed-center position blocks flow and can hold trapped pressure in the connected circuit.
• PRV (pressure relief / release valve) — Provides pressure control or overpressure protection depending on how the particular system is configured.
• Regulator — Controls the working pressure supplied during the operation.
• Pump unit — Uses compressed air to produce hydraulic oil flow. SC Hydraulic pumps are commonly used in setups like this one.

How This Unit Is Typically Used

• Check the regulator, PRV, hoses, fittings, and gauges before connecting the system to the equipment being tested.
• Move the selector valve to the position required for the job: advance, retract, or center.
• Bring the pressure up gradually while watching the gauges and connections.
• If the reading changes unexpectedly or a fitting begins leaking, stop and investigate before continuing.
• When the work is finished, release pressure using the bleed procedure specified for the test system, cylinder, or tensioning equipment.

Never disconnect a hydraulic line or fitting until the circuit has been fully depressurized.

Safety and Best Practices

Before a test begins, verify the pressure-control settings and make sure the selector valve moves through its positions correctly.

The regulator should not be able to change accidentally once the required setting has been established. Hoses, fittings, and quick-connects should also be checked for visible damage or leakage before pressure is applied.

Keep hands away from suspected leaks while the system is pressurized. High-pressure hydraulic fluid can penetrate the skin.

If the pump is being used with hydraulic tensioners, follow the tensioner manufacturer’s instructions for pressurizing, bleeding, and releasing the system.

Maintenance Checklist

• Give the hoses, fittings, gauges, and reservoir a quick inspection before the job starts.
• Check the oil level and look for signs of dirt, moisture, or other contamination in the fluid.
• Confirm the regulator and PRV settings before putting the system into critical service.
• Check gauge calibration at the interval required for the application.
• Cycle the selector valve during preventive maintenance and make sure it moves freely through its intended positions.
• Watch for oil around valve stems, fittings, and connections that could point to a developing leak.For more information on hydraulic fluid, see Hydraulic torque wrench pump oil — The best oil for your pump.

If the Cylinder Is Barely Moving

• Slow or no cylinder movement: If the pump is cycling but the cylinder only creeps, watch the air-pressure reading while the pump is under load. A noticeable drop there points to the air supply before you start looking for a restriction on the hydraulic side.
• Pressure will not stay where it was set: Check the regulator setting and look for leakage in the hydraulic circuit. The pressure-control components should also be checked against the system procedure.
• PRV opens repeatedly: Verify the operating pressure and selector-valve position. Repeated relief can indicate that the system is reaching the PRV setting during operation.
• Cylinder moves in the wrong direction: Check the selector-valve position and confirm that the advance and retract hoses are connected to the intended ports.

When to Contact Winshaw

If you need help putting together an air powered pump cabinet or matching a pump to double-acting cylinders, contact Winshaw at sales@winshawllc.com.

For more background on double-acting cylinder operation, see How Does a Double Acting Hydraulic Cylinder Work?.

For hydraulic tensioning applications, see Considerations When Using Hydraulic Bolt Tensioners.

About This Setup

This article covers the basic components and operation of a cabinetized double-acting air powered hydraulic pump setup. Individual systems can use different pumps, valves, pressure controls, and cylinder arrangements.

Use the pump, cylinder, and system manufacturer’s documentation for the pressure ratings, connection requirements, operating procedure, and service instructions for the specific equipment being used.